In this part of my series Implementing Technical Indicators I provide you with the R implementation of another technical indicator. Please refer to my article Technical Indicators: An Introduction for an overview of the concept of technical indicators and for details on the particular one presented in this article.
For an implementation of the average true range (ATR) please see the R code below. The function ATR calculates the indicator values, which may afterwards be plotted with help of the function plotATR. Note that both function use tools introduced in my article Implementing Technical Indicators: Tools.
#
# AVERAGE TRUE RANGE
#
# measurement of trading range
#
source("Indicators/IndicatorHelperFunctions.R")
source("Indicators/IndicatorPlottingFunctions.R")
# indicator calculation
ATR = function(v_high, v_low, v_close, i_window=10)
{
checkVectors(v_high, v_low, v_close)
checkWindow(v_close, i_window)
i_length = length(v_high)
m_ranges = matrix(c(v_high - v_low, abs(c(0, v_high[2:i_length] - v_close[1:(i_length-1)])),
abs(c(0, v_low[2:i_length] - v_close[1:(i_length-1)]))), nrow=3, byrow=TRUE)
v_true_range = apply(m_ranges, 2, max)
v_atr = rep(0, i_length)
v_atr[1] = mean(v_true_range[1:i_window])
for (i in 2 : i_length) {
v_atr[i] = (v_atr[i-1] * (i_window-1) + v_true_range[i]) / i_window
}
df_atr = data.frame(v_atr, v_high, v_low, v_close)
colnames(df_atr) = c("ATR", "High", "Low", "Close")
return(df_atr)
}
# indicator plotting
plotATR = function(v_date, df_atr, s_path)
{
isDataFrame(df_atr)
dateMatch(v_date, df_atr)
v_colors = c("black", "blue", "purple", "green")
v_legend = c("ATR", "High", "Low", "Close")
plotIndicator2(v_date, df_atr$ATR, df_atr[, -1], v_colors, v_legend, s_path)
}